I have always been under the policy that a single or two-some has no priority on the golf course. If I am playing and they are behind me and there is room in front to let them go through and they will actually not impede me, I will let them through. However, if there are groups ahead of me, even if they are a hole ahead or so, I am not letting them play through. They can form a foursome at the first tee or get more players to play with them. Just my opinion and YRMV.